Parts of an Atom UNIT 1 NOTES

What does an atom look like?

Remember Jimmy Neutron? Is this an accurate representation of an atom?

Atoms - the building blocks of matter What are atoms? Atoms - the building blocks of matter Li Li

Matter - anything that has mass and volume Structure of Matter Matter - anything that has mass and volume

Atomic Structure Atom - the smallest particle of an element, having all the properties of that element

Atomic Structure Subatomic Particles - any particle that is smaller than an atom (over 200 kinds are known)

Atomic Structure Nucleus - very small, dense, positively charged center of an atom Makes up approximately 99% of an atom’s mass, but a very small amount of its volume

Atomic Structure: Inside the Nucleus The nucleus is made up of… Protons - subatomic particles with a positive charge (proton = positive) Neutrons - subatomic particle with no charge (neutron = neutral)

Atomic Structure Electrons - subatomic particles with a negative charge Orbit the atom’s nucleus

Electron cloud - the space in which electrons are likely to be found Atomic Structure Electron cloud - the space in which electrons are likely to be found

Periodic Table - Contains information about each of the elements

Periodic Table Elements on the periodic table are each uniquely defined by their atomic number (number of protons)

Periodic Table: Elements Atomic Number - Equal to the number of protons in the nucleus, as well as the number of electrons in the electron cloud Symbol - A one or two letter abbreviation derived from the element’s English or Latin name Name - Element’s common name Atomic Mass - Weighted average of the masses of all the element’s isotopes

ATOMIC MASS = # PROTONS + # NEUTRONS What is the atomic mass? Atomic Mass - Weighted average of the masses of all the element’s isotopes Nucleus is 99% of the mass of the atom Nucleus is made up of protons and neutrons This means that the mass of the atom is approximately equal to the mass of the protons plus the neutrons Mass of proton = 1 atomic mass unit (amu) Mass of neutron = 1 atomic mass unit (amu) ATOMIC MASS = # PROTONS + # NEUTRONS

Summary Atomic Number = Number of protons Atomic Number = Number of electrons Symbol = Big letter(s) in the center Name = Name of element Atomic Mass = Number of protons plus number of neutrons